Multi-port gas burner



Nov. 15, 1966 1.. P. HINE, JR, ETAL MULTI-PORT GAS BURNER 2 Sheets-Sheet1 Filed Oct. 9, 1963 INVENTORS.

Louis P. Hines dr.

BY Richard J. Vales flm; m y

ATTORNEYS.

Nov. 15, 1966 Filed Oct. 9, 1965 L. P. HINE, JR., ETAL 3,285,317

MULTI-PORT GAS BURNER 2 Sheets-Sheet 2 Fig. 6

INVENTORS Lou/5 P. Hwss J2. BY PLCHAED J. VALES ATTORNEY United StatesPatent 3,285,317 MULTI-PORT GAS BURNER Louis P. Hine, Jr., and RichardJ. Vales, Elyria, Ohio, assignors to The C. A. Olsen Mfg. Company,Elyria, Ohio, a corporation Filed Oct. 9, 1963, Ser. No. 314,996 8Claims. (Cl. 158-99) This application is a continuation-in-part ofapplication Serial No. 155,015, filed November 27, 1961, and now PatentNo. 3,177,923.

This invention relates to gas heating and particularly to gas burnersfor furnaces.

It is an object of the invention to obtain increased efliciency andimproved characteristics of combustion of fuel gases.

A further object is to avoid tendency for flash-back.

Still another object is to overcome a tendency for resonance or noise. I

Still another object of the invention'is the incineration of entrainedlint, the prevention of clogging of gas burners, and simplification andreduction of costs of construction of durable, sturdy gas burners oflight weight, which are safe in operation.

Still another object is to provide a universal burner suitable for anytype of gas.

Other and further objects, features and advantages of the invention willbecome apparent as the description proceeds.

In carrying out the invention in accordance with a preferred formthereof, an elongated horizontal burner is provided which is fabricatedfrom sheet material such as carbon steel or other cold rolled steel toform a mixing tube tapering to a relatively small closed end with anopen top closed by burner strip having elongated slots therein. Theslots or ports are arranged in parallel rows lengthwise along the burnerstrip and there are at least three rows of such elongated ports orslots. The burner strip is dished or formed concave so that the centerports are lower than the side ports and resonance of the flames isavoided by the difference in height of the flames at the center and sideports. The ports near the gas inlet end of the mixing tube are madenarrower to minimize tendency for flashback.

Preferably the burner strip is composed of materials such as chrome typestainless steel, which is not corroded by sulphur-containing gases andwithstands high temperatures, permitting use as a universal burner forany type gas. The slots are relatively long, but of considerably lesslength than the extent of the mixing tube so as to provide enough webs,or material between successive slots in the same row, for adequatestructural strength. The use of non-corrosive strip material preventsalteration of slot size or contour in event of contact with corrosivegas.

The burner strip is composed of relatively thin gage stock so as tomaintain a relatively high temperature on the inner surface of theburner strip. Nevertheless, there is a high temperature differencebetween the slots and the edge of the strip so that the mixing tube runscool. The slots are as narrow or narrower than the thickness of theburner strip and the flashback tendency is in this manner furtherdiminished even for relatively fast flame propagation gases such asmanufactured gas and propane gas.

In operation any lint .in the atmosphere is entrained in the column ofmixed air and combustible gas traveling lengthwise in the mixer tube.The burner strip forms a zone of high temperature difference betweenslot edges and mixer tube, incinerating lint carried upwardly toward theslots from the column and the streams of mixed air and gas. Ignition ofthe air and gas mixture on the outer side of the zone formed by theburner strip produces in= cinerating temperature on the inner side sothat the lint is incinerated, leaving only light ash which can travelthrough the port without clogging. A better understanding of theinvention will be afforded by the following detailed descriptionconsidered in conjunction with the accompanying drawing in which:

FIG. 1 is an elevation of a furnace burner forming an embodiment of theinvention.

FIG. 2 is a plan view of the burner of FIG. 1.

FIG. 3 is a view of a cross-section of the burner of FIGS. 1 and 2 cutby a plane 33 represented in FIG. 1.

FIG. 4 is a view of a section of the burner of FIG. 1 cut by a plane 44passing through the narrower portion of the mixing tube, the plane 44being indicated in FIG. 1.

FIG. 5 is an end view of the burner of FIG. 1 showing the arrangement ofthe air mixture control valve.

FIG. 6 is a fragmentary view to an enlarged scale of the burner of FIG.2 showing variation in slot Width exaggerated.

Like reference characters are utilized throughout the drawing todesignate like parts.

The burner comprises a mixing tube 11 having a relatively small closedend 12 and an open end 13 with a venturi throat 14. The open end 13 hasa relatively large diameter to receive a conventional rotatable-diaphramtype of shutter 15 for controlling the ratio of air to gas in themixture admitted in the mixing tube 11. The shutter 15 has conventionalcenter opening 16 into which the nipple of a gas pipe (not shown)projects.

The diameter of the mixing tube 11 increases from the venturi throatportion 14 to a point 17 of maximum diameter, after which it againtapers to a relatively small diameter at the end 12. As shown in FIG. 3,the portion of the mixing tube 11 between the maximum diameter point 17and the end 12 has a longitudinally extending lateral opening 18 coveredby a strip 19. Long, narrow slots 20 in a plurality of rows, at leastthree, are provided in the burner strip 19 to form ports from whichseparate streams of air-gas mixture issue to form a flame.

Preferably the portion of the material forming the tube 11 adjacent thelateral opening 18 is bent transversely outward to form ribs 22 forspacing the burner strip 19 from the remainder of the mixing tube 11.The burner strip 19 is joined to the edge of the ribs 22 in any suitablemanner to form a gas-tight joint. Preferably, the edges 23 of the ribsare bent transversely, sloping slightly upward, and the edges 24 of theburner strip 19 are crimped around the edge portions 23.

and gas flowing upwardly from the column of mixed air I The burner strip19 is dished or made concave so that the center slots are lower than theouter slots or ports and any tendency for the issuing gas or flame toform resonating columns and to produce obnoxious noise or to sing isavoided by the interference between vibration of any air columns or gascolumns at the center ports and the side ports. These columns are ofdiflerent lengths because the center ports are lower. Therefore,resonance is prevented. To facilitate assembly and formation of tightjoints at the ends of the strip 19, the ends may be partially or whollyflattened.

In order to achieve low manufacturing costs, durability and lightness,the mixing tube 11 is preferably fabricated from two pieces of sheetmaterial such as pieces 25 and 26 composed of cold rolled, carbon-steelsheet. The pieces 25 and 26 are stamped or pressed to shape to provide afrusto-conical, or circular-cross section, cavity 31 in the centralportion of the two sheets 25 and 26 to form the hollow mixing tubeinterior with flat side portions 27 and clogging does not occur.

3 28 and with the ribs 22. The end 12 is closed. The flattened portions27 and 28 are joined in any suitable manner as by means of crimped overedges 23.

In the embodiment illustrated the slots 20 consist of three rows ofslots, each row consisting of 17 slots in alignment.

For guarding against flash-back even with fast burning gases with a highrate of flame propagation such as manufactured gas having highpercentage of hydrogen, the slots 20 are made narrow, being no widerthan the thickness of the strip 19, preferably slightly less. As shownin the drawing, the thickness of the strip is the depth of the slots andthe width of the slots is no greater than their depth. As a furthersafeguard, the slots 21 at the manifold or inlet end of the burner strip19 are made slightly narrower than those in the central portion with theslot width becoming progressively narrower toward the manifold end orthe inlet end at which the shutter 15 is located.

The invention is not limited to specific dimensions, but in the form ofgas burner for furnaces forming a specific embodiment illustrated theslots 20 are approximately of an inch in length with approximately /8inch spacing between successive slots in each row and with approximately%2 inches between adjacent edges of the slots in adjacent rows. Thedistance of the center portion of the burner strip 19 below the sideedges of the burner strip is approximately the width of the burner stripand the slots 20 occupy approximately to /3 of the width of the burnerstrip 19.

Where the burner strip 19 is made of 20 gage stainless steel strip theports are approximately of an inch wide in the central portion of theburner and the width is decreased to approximately of an inch at the endnear the manifold, which is approximately ten percent less. In practice,in order to balance the port plates or burner strips, they are made withnarrower ports or orifices at each end so that they are symmetrical andthere is no danger of an error being made by mounting the strip in thewrong direction.

For structural strength and also for correct thermal balance, themaximum feasible length of slot and minimum web or spacing betweensuccessive slots in the same row depends upon slot arrangement and stripthickness. To avoid distortion of slot width we believe that thinnerstrips will require shorter slots, and greater web dimension thanthicker strips. Generally, the optimum slot length is or more times theslot width for most eflicient operation.

The sheet material comprising the pieces 25 and 26 is smooth surfacedand preferably coated with a smooth lacquer or other coating material.Consequently, lint drawn into the openings of the shutter assembly fromthe air tends not to adhere to the inner surfaces of the mixing tube 11and a clogging of the interior does not occur. However, lint tends to bedrawn to the ports in the burner strip 19. As will be explained morefully hereinafter, the lint is incinerated at the ports and port Whenthe ports are punched, they may be punched from the inner surface of thestrip toward the outer surface in order to avoid forming a burr on theinner surface which might catch lint or arrest its progress through theport opening and to the point of maximum temperature for disintegration.

The burner strip 19 is composedof very thin material, as described, sothat the inner surface runs substantially as hot as the outer surface asa result of the flames issuing from the ports 21. Moreover, the materialof which the low or lower as that of the carbon steel tube 11 so thatthere is a high temperature gradient between the slots or ports 20 andthe edges 24 of the burner strip 19. Thus, the tube 11 runs relativelycool, notwithstanding the high temperature of the slot portion of theburner strip 19 at the base of the flame.

A suitable material for the burner strip 19 has been found to bestainless steel particularly the chromium type of stainless steel whichis not corroded when exposed to sulphur-bearing gases and will withstandhigher temperature than carbon steel without explosion of the metal.This is especially important when low pressure or bottled gas ormanufactured gas is used which may have a flame temperature of about1200 F., not far from the critical temperature for carbon steel. Heatresisting steel, moreover, minimizes grain growth and therefor minimizespermanent deformation. It also has a somewhat lower conductivity thancarbon steel. In the embodiment illustrated, the burner strip 19 iscomposed of 20 gage stainless steel, which is approximately .035 inch inthickness. Such thin strip runs very hot at the lower surfaceimmediately adjacent the slot 20 and causes incineration of any lintdrawn to the slot 20.

We have found that with three rows of ports the flame is brought downclose to the ports to increase the temperature of the burner strip andobtain satisfactory consumption of lint. The arrangement permitsdelivering suflicient gas to generate 25,000 B.t.u.s an hour for eachsquare inch of port area without blowing the flame away from port aswell as permitting greatly reduced gas delivery without flash-back.

In order to permit use of one pilot burner for several adjacent burners,each burner may be provided with a carry-over slot 35 which overhangs aport for transferring flame to an adjacent burner to ignite it.

While the invention has been described as embodied in concrete form andas operating in a specific manner in accordance with the provisions ofthe patent statutes, it should be understood that the invention is notlimited thereto, since various modifications will suggest themselves tothose skilled in the art without departing from the spirit of theinvention.

What is claimed is:

.1. A gas burner comprising a mixing tube having a gas inlet opening anda longitudinal outlet opening, and a burner strip across said outletopening composed of sheet material and having elongated parallel slotstherein no wider than the depth of the slots, the slots beingapproximately ten percent narrower at the end near the gas inlet openingand of such an order of magnitude as ordinarily to preclude flash back.

2. A gas burner comprising a mixing tube extending longitudinally,closed at one end and having an inlet opening at the other end foradmitting gas and a longitudinal outlet opening extending lengthwisealong the side of the tube, and a burner strip across said outletopening composed of sheet material and having elongated parallel slotstherein no wider than the depth of the slots, said slots beingapproximately ten percent narrower toward the gas inlet opening and ofsuch an order of magnitude as ordinarily to preclude flash back.

3. A gas burner comprising a mixing tube extending longitudinally,closed at one end and having an inlet opening at the other end foradmitting gas and a longitudinal outlet opening extending lengthwisealong the side of the tube, and a burner strip across said outletopening having elongated parallel slots therein, the slots being of theorder of of an inch across in the central portion of the mixing tube andof the order of 1 of an inch across at the gas inlet opening end of themixing tube.

4. A gas burner comprising a frusto-conical mixing tube extendinglongitudinally between a closed end and a second end having a gas inletopening and having a longitudinal outlet opening extending along theside of the tube, and a burner strip across said outlet opening havingelongated parallel slots therein extending lengthwise of the mixingtube, said strip being concave to lower the central slots below the sideslots of the burner strip sufliciently to change the length ofthe aircolumn at the central slots, the slots being approximately ten percentnarrower at the end near the gas inlet opening and of such an order 0magnitude as ordinarily to preclude flash back.

5. A burner as in claim 4 wherein the burner strip is dished to theextent of about A its Width.

6. A burner as in claim 4 wherein the longitudinally extending slotsoccupy between /3 and A the width of the burner strip.

7. A burner as in claim 4 wherein the burner strip has at least 3parallel rows of longitudinally extending slots.

8. A gas burner comprising a mixing tube extending.

longitudinally, closed at one end and having an inlet opening at theother end for admitting gas and a longitudinal outlet opening extendinglengthwise along the side of the tube, and a unitary burner strip acrosssaid outlet opening composed of sheet material .and having elongatedparallel slots therein, said slots being no wider than the depth of theslots and being approximately ten percent narrower towards the ends ofthe burner strip and of such an order of magnitude as ordinarily topreclude flash back.

References Cited by the Examiner UNITED STATES PATENTS 702,873 6/1902Holland 158-1 16 762,183 6/ 1904 Montgomerie et al. 1,568,771 1/1926 Roy158116 2,044,528 6/1936 Guhl 15899 X 2,373,492 4/1945 Nelson et -al158114 X 2,755,851 7/1956 Dow et al 158114 2,781,833 2/1957 Feyling157117 X 2,828,532 4/1958 Taylor 158116 X 2,869,630 1/1959 Flynn 1581053,053,316 9/1962 Flynn 158116 FOREIGN PATENTS 12,327 2/1903 Austria.

FREDERICK L. MATTESON, JR., Primary Examiner.

1. A GAS BURNER COMPRISING A MIXING TUBE HAVING A GAS INLET OPENING ANDA LONGITUDINAL OUTLET OPENING, AND A BURNER STRIP ACROSS SAID OUTLETOPENINGS COMPOSED OF SHEET MATERIAL AND HAVING ELONGATED PARALLEL SLOTSTHEREIN NO WIDER THAN THE DEPTH OF THE SLOTS, THE SLOTS BEINGAPPROXIMATELY TEN PERCENT NARROWER AT THE END NEAR THE GAS INLET OPENINGAND OF SUCH AN ORDER OF MAGNITUDE AS ORDINARILY TO PRECLUDE FLASH BACK.